The number of people who have died after taking legal highs has more than tripled in just two years.

And official figures from the Office for National Statistics (ONS) reveals than men in their twenties are the group most likely to die after taking the substances.

In 2011, seven people died as a result of talking a legal high but by 2013, there were 23 deaths linked to the drugs in England and Wales. And the statistics show that the average age of the victims was just 28 whereas the average age for other drugs deaths in 38.

Between 2004 and 2014, a total of 76 people have died after consuming a legal high, a substance containing chemicals which alters the mood of users but is not against the law. The youngest of these victims was 18.

Vanessa Fearn, who works as a mortality researcher at the ONS, said people may be tricked into thinking these substances are not dangerous because they can be bought legally in England and Wales.

She said: “Forensic testing has shown that a single tablet or powder can contain a mixture of different substances, and even ‘traditional’ illegal drugs, which may explain why the majority of deaths involving legal highs involved more than one drug.”

Although, experts are concerned by the growing number of deaths involving legal highs, they are still linked to far fewer fatalities than illegal substances like heroin and cocaine. Between 2004 and 2014, 7,748 people died after taking either heroin or morphine while there were 1,752 deaths involving cocaine.

New legislation was delayed

A new law which will ban legal highs was due to be introduced last month but it has been delayed while further work is done on the finer details of the legislation. If it is introduced, The Psychoactive Substances Act 2016 will make it illegal to produce, supply, import or export a substance intended for human consumption which has a psychoactive effect.

The law will exclude some legitimate substances including alcohol, caffeine and prescription drugs.

A report from the ONS says one of the reasons legal highs are so dangerous is that people often don’t know exactly what they are taking.

It said: “Little research has been carried out into the short or long-term harms of ‘legal highs’. So users are effectively acting as human guinea pigs, because they cannot be sure what substance they are actually taking, how much to take, or the effect it will have.”

The wide variety of legal highs available make them difficult to test for. They cannot be labelled as suitable for human consumption and are often sold as plant food, incense or bath salts.

However, as more is learnt about the legal highs on the market, drugs tests can be developed to check whether someone has taken the substance.

AlphaBiolabs tests for a range of drugs, including mephedrone, which was the first legal high to come to the attention of the public. Known as Meow Meow or M-Cat, it was classified as a class B drug in 2010.

In 2012, 22 people died after taking mephedrone, although this number fell to 12 in 2013.